There are now several catheters being developed by several different companies whose goal is to perform renal nerve denervation to reduce the blood pressure for hypertensive patients. Therefore, it will become increasingly important over the next several years to create improved means for renal denervation catheters to access the renal arteries.
The current practice for accessing the renal arteries is to first use an arterial access needle puncture at the groin, and then a guide wire is placed through that needle into the femoral artery. The needle is then removed while the guide wire remains in place in the femoral artery at the groin. An introducer sheath with dilator would then be advanced over the guide wire and into the lumen of the femoral artery. The dilator and the guide wire would then be removed and a guiding catheter would be advanced through the introducer sheath until its distal end would be placed into a renal artery. A catheter for renal denervation could then be advanced through the guiding catheter and it would be used to kill a section of the renal nerves that surround the renal artery thus permanently lowering the blood pressure of a patient that is hypertensive.
The renal denervation catheters require a fairly large diameter guiding catheter; typically 6, 7 or 8 French size. Since the outer diameter of the sheath through which the guiding catheter is inserted is typically 2 to 3 French sizes larger than the outer diameter of the guiding catheter, a fairly large diameter hole must be made through the wall of the femoral artery. These larger size holes can lead to excessive bleeding at the groin after the guiding catheter and the sheath are removed.
At this time, all guiding catheters designed for accessing the renal arteries terminate at their proximal end with a Luer fitting. To perforin an intra-arterial procedure with any existing guiding catheter, it is necessary to attach a Tuohy-Borst “Y” adaptor onto the Luer fitting at the guiding catheter's proximal end. The introducer sheath and Tuohy-Borst “Y” adaptor are each components that require additional time for the interventional cardiologist to properly place, and they add to the cost of performing intra-arterial procedures. Also, the introducer sheath through which the guiding catheter is inserted typically must have a three-way stopcock attached to a Luer fitting on a side arm tube that is located near the proximal end of the introducer sheath. The additions of a Tuohy-Borst “Y” adaptor to the guiding catheter and adding a three-way stopcock to the side tube of the introducer sheath adds additional cost and time to any procedure for accessing the renal artery. If a means for accessing the renal artery could be accomplished without requiring an introducer sheath and without requiring the additional parts of a Tuohy-Borst “Y” adaptor and a three-way stopcock, the procedure could be done in less time and at a lower cost.
In U.S. Pat. No. 5,389,090, Fischell et al describe an improved guiding catheter that is particularly useful for accessing the coronary arteries. However, there are no specific features of that invention that are specifically devoted for improved access for the renal arteries. Specifically, the invention described in the '090 patent does not teach markings on the shaft of the guiding catheter to assist in the placement of that guiding catheter into the renal arteries. The '090 patent also fails to teach the importance of a side arm tube that lies in the same plane as does the curve at the distal section of the guiding catheter, which feature enables the operator to have the correct azimuth angle for placement of the distal end of the guiding catheter into and through the ostium of the renal artery. Still further, the '090 patent fails to teach a three-way stopcock formed integral with the side arm tube at the guiding catheter's proximal end that precludes the need for the operator to open a separate package to attach that device to the guiding catheter. A guiding catheter design that would not require the use of an introducer sheath and would have a Tuohy-Borst fitting and a three-way stopcock each formed integral with the guiding catheter at its proximal end would result in savings of both time and cost for the procedure to access the renal arteries.